1. Field of the Invention
The present invention relates to an RF signal blocking device having a function of blocking an RF signal in a prescribed frequency band after an RF signal having an RF power value greater than or equal to a predetermined level is inputted.
2. Description of the Related Art
As illustrated in one example of a coil with a fuse function shown in FIG. 7, a coil 500 with a fuse function has been known which is configured such that a solenoid coil 503 is enclosed in a cylindrical glass tube 505 provided with conductive caps 504 at opposite ends. See, for example, Japanese Patent Laying-Open No. 9-330824. The solenoid coil 503 is including a fuse line 502 wound around an outer peripheral surface of a cylindrical ferrite core 501. Coil 500 with a fuse function has both a normal fuse function for protection from a short circuit current and an overload and a coil function which is useful for suppression of an inrush current and noise reduction, thus one element can achieve two functions. Therefore, a space for disposing coil 500 with a fuse function is reduced, so that high-density packaging of electronic equipment can be readily performed, enabling miniaturization of a device.
In recent years, communication mobile terminals such as mobile phones and mobile information terminals with a higher frequency have been developed. In a case where coil 500 with a fuse function described above is used for communication mobile terminals with higher frequency, the following problem may arise. In other words, even in a case where fuse line 502 is fused due to a flow of an overcurrent to coil 500 with a fuse function, when a high-frequency signal (RF signal) is provided, the fused portion of fuse line 502 may possibly be coupled by capacitive coupling, magnetic field coupling, or both to thereby transmit an RF signal through the fused portion of fuse line 502.